Advances in plasma processing have facilitated growth in the semiconductor industry. Generally speaking, a plurality of semiconductor devices may be created from dies cut from a single processed substrate. To process a substrate, the substrate may be placed on top of a substrate chuck within a plasma processing chamber. The positioning of the substrate on the substrate chuck may determine which portion of the substrate may be processed to form devices.
Methods are available for aligning a substrate to the center of a substrate chuck. In an example, sensors may be placed in a processing module to determine the positioning of a substrate in regard to a substrate chuck. In another example, an alignment fixture, such as a guided robotic arm may be employed to position the substrate in alignment with the substrate chuck. Although aligning to a hardware center (e.g., center of the substrate chuck) may be performed with some precision, alignment to the hardware center may not always equate to an alignment to the process center.
As discussed herein, the hardware center refers to the center of a hardware, such as a substrate chuck. Also as discussed herein, the process center refers to the focal center of the plasma process. Ideally, at any given radial distance from the focal center, the process result (e.g., the etch rate) remains the same. For example, at a distance of 100 mm from the process center, it is expected that the etch rate remains substantially constant as one follows around a circle having a radius of 100 mm from this focal process center. Due to chamber configuration peculiarities, the process center may not always be the same as the hardware center. As a result, basing alignment on the hardware center alone may cause misalignment during substrate processing. As manufacturers continue to strive to improve yield, efforts are continually made to more precisely center the substrate over the process center during plasma processing to minimize device defect caused by substrate misalignment.